The best way to listen to your iPod through your vehicle's factory stereo is using a direct audio input which provides the highest level of sound quality. Most direct audio inputs require the factory radio to be equipped with an external CD changer or at least be CD changer ready (able to control a factory CD changer even if it doesn't come factory equipped). There are two direct input solutions- audio input only which relies on using the iPod's click wheel for navigation, and direct interface which allows the factory radio to control the iPod's basic functions and in some cases display the iPod's information on the factory radio.